The GICv2 and GICv3 architectures allow an active physical interrupt to be forwarded to a guest, and the guest to indirectly perform the deactivation of the interrupt by performing an EOI on the virtual interrupt (see for example the GICv2 spec, 3.2.1). This allows some substantial performance improvement for level triggered interrupts that otherwise have to be masked/unmasked in VFIO, not to mention the required trap back to KVM when the guest performs an EOI. To enable this, the GICs need to be switched to a different EOImode, where a taken interrupt can be left "active" (which prevents the same interrupt from being taken again), while other interrupts are still being processed normally. We also use the new irq_set_vcpu_affinity hook that was introduced for Intel's "Posted Interrupts" to determine whether or not to perform the deactivation at EOI-time. As all of this only makes sense when the kernel can behave as a hypervisor, we only enable this mode on detecting that the kernel was actually booted in HYP mode, and that the GIC supports this feature. This series is a complete rework of a RFC I sent over a year ago: http://lists.infradead.org/pipermail/linux-arm-kernel/2014-June/266328.html Since then, a lot has been either merged (the irqchip_state) or reworked (my active-timer series: http://www.spinics.net/lists/kvm/msg118768.html), and this implements the last few bits for Eric Auger's series to finally make it into the kernel: https://lkml.org/lkml/2015/7/2/268 https://lkml.org/lkml/2015/7/6/291 With all these patches combined, physical interrupt routing from the kernel into a VM becomes possible. This has been tested on Juno (GICv2) and FastModel (GICv3). A branch is available at: git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git irq/gic-irq-vcpu-affinity Marc Zyngier (6): irqchip: GICv3: Convert to EOImode == 1 irqchip: GIC: Convert to EOImode == 1 irqchip: GICv3: Skip LPI deactivation irqchip: GIC: Use chip_data instead of handler_data for cascaded interrupts irqchip: GICv3: Don't deactivate interrupts forwarded to a guest irqchip: GIC: Don't deactivate interrupts forwarded to a guest drivers/irqchip/irq-gic-v3.c | 57 +++++++++++++++++++++++++++++++-- drivers/irqchip/irq-gic.c | 64 +++++++++++++++++++++++++++++++++++--- include/linux/irqchip/arm-gic-v3.h | 9 ++++++ include/linux/irqchip/arm-gic.h | 4 +++ 4 files changed, 126 insertions(+), 8 deletions(-) -- 2.1.4 _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
